Steps to reproduce:

• open something long enough to not fit into the editbox
• go to the end
• start selecting upwards (e.g. with Shift-PgUp or Shift-Up)

Expected behavior: when the selection reaches the top of the edit box, the box starts scrolling upwards (this is how native textareas behave).

Actual behavior: selection passes by the top of the box, after which I can't see what I'm doing anymore. Even if I scroll the window manually, it jumps to scroll the end of the selection into view as soon as the selection changes.
(When changing the start of the selection, scrolling works as expected.)

Tested on Chrome 64.0.3282.119 (64-bit, Ubuntu 16.04).

(There is also blinking/flashing of the screen going on when I move the selection, both when moving the start and the end; but that's just ugly, it does not interfere with selecting the text.)